Have you tried clearing your Xbox 360 cache by following the steps listed here How to Clear Xbox 360 System Cache? What region in world are you playing from? Have you tried resetting your router? Also, can you tell what your NAT type is currently at?

I'm feeling the same way Yarse. this has been going on for at least a week now despite the servers being on defcom 5 and is becoming more then frustration. Please could some one help with this, I'm in the UK, hard wired to a high speed cable modem with an open NAT.